Re: \mark and slur

[Thomas Morley]

2017-09-16 13:28 GMT+02:00 David Kastrup <address@hidden>:
> Thomas Morley <address@hidden> writes:
>
>> Other 5181-topic:
>> In your patch description you wrote about the problem with
>> c-\single \dynamicUp \f
>>
>> Here I can't follow, compiling this with 2.18.2 and current master
>> returns no noticeable difference for me, even using
>> display(Lily)Music.
>> May be I overlooked something.
>> Could you explain a bit more verbose?
>
> From the commit message:
>
>     Issue 5181/2: Allow lone postevents in braced lists
>
>     Reattaching post-events to a preceding music variable or music
>     function call (or expression) is often desired but was unsupported.
>
>     This commit caters for the support in braced lists.
>
>     The problem with supporting such expressions _everywhere_ is that it
>     breaks the use of
>
> The grammar used here is slightly wrong because it uses indicative mode
> for an irrealis.  It should rather be:
>
> The problem with supporting such expressions _everywhere_ would be that
> it would break the use of ... since then \f would be attached to
> \dynamicUp instead of ...
>
>         c-\single \dynamicUp \f
>
>     since then \f is attached to \dynamicUp instead of becoming the second
>     argument to \single, due to operator precedence.  So reattaching lone
>     post-events is only done with lower precedence in selected constructs.
>
> This part of the commit message explains why it has not been possible to
> support things like
>
>     xxx = c4
>
>     { \void \displayLilyMusic \xxx \f }
>
> even while \xxx \f now works.  If the grammar precendences in this case
> would have combined \xxx \f, they would also combine \dynamicUp \f in
> the use case involving \single since \dynamicUp is a bona-fide
> (non-post-event) music expression.
>
> So I just committed with unsuitable grammar for a hypothetical.  You
> will not be able to see the described problem with anything committed to
> the central repository, but there may be a few instances in the reflog
> of my personal repository.  Basically I wanted to commit an
> implementation that happened not to pass the regtests, so I had to scrap
> that approach after convincing myself that this could not otherwise be
> made to work.
>
> --
> David Kastrup

Thanks for the explanations.

(1)
In this thread we mostly discussed what happens for examples like:
{ -"foo" r4 }
especially which sort of warning should be printed.
(I'm fine with 5194 and will comment in this way)
But let me focus on other parts:

(2)
If I understand correctly, with this patch things like below are now possible:

xxx = c4
{ \xxx -- }

and

foo =
#(define-music-function (mus)(ly:music?)
  (music-map
    (lambda (m)
      (if (music-is-of-type? m 'note-event)
          #{ $m -. #}
          m))
    mus)
  #{
        \new ChordNames {
            \tweak self-alignment-X #LEFT
          \mark "This function is a limited demo, don't use it for any
other stuff."
        }
        $mus
  #})

\foo \new Staff \relative c' { c d e f g a b c }

Which is a big, big goody!

(3)
In the light of your explanations above I was afraid the following
would fail (meaning the displayed expression wouldn't be complete):

buzz =
#(define-music-function (mus)(ly:music?)
  (music-map
    (lambda (m)
      (if (music-is-of-type? m 'note-event)
          (begin
            (display-scheme-music (ly:music-property m 'articulations))
            m)
          m))
    mus)
  #{
        \new ChordNames {
            \tweak self-alignment-X #LEFT
          \mark "This function is a limited demo, don't use it for any
other stuff."
        }
        $mus
  #})

yyy = c4

\buzz \new Staff { \yyy -\single \dynamicUp \f }

But as far as I can tell, all works.

So I can live with the problem of

xxx = c4
{ \void \displayLilyMusic \xxx \f }



Great stuff!!


Cheers,
  Harm